1. Field of the Invention
The present invention relates to a circuit board, particularly to a circuit board with an improved ground plane.
2. Description of Related Art
Circuit boards such as printed circuit boards (PCBs) are widely used in conventional electronic devices. In designing a contemporary PCB, controlling trace impedance is very important. The impedance relates to a number of parameters, such as the widths and distances of signal traces, and the thicknesses of media layers of the PCB. For example, a circuit board includes a signal plane for signal traces arranged thereon and a ground plane for ground traces arranged thereon. A media layer is disposed between the signal plane and the ground plane. Generally, the thickness of the media layer is so thin, that the impedance of the signal traces is reduced too much. That may affect the signal quality of the circuit board.
What is needed, therefore, is a circuit board having proper signal trace impedance for improving signal quality.